For example, FIG. 8 shows such a conventional chain with a seal as is disclosed in Japanese Utility Model Laid Open No. 134552/75, in which a rubber seal 4 is attached to an inside surface 3A of an outer plate 3 which is opposed to an inner plate 2 on a connection pin 1 of the chain, and an annular sealing projection 4A is projected from the rubber seal 4 so as to abut an outside surface 2A of the inner plate 2 opposed to the outer plate 3 and in a surrounding relation to the connection pin 1.
In the prior art referred to above, since the rubber seal 4 is attached to and held by only the inside surface 3A of the outer plate which surface is a flat surface, there is a fear that the rubber seal 4 may peel and fall off the flat surface of the outer plate 3 due to a difference in the thermal expansion coefficient between the outer plate and the rubber seal.
Once the rubber seal 4 comes off the outer plate 3, the rubber seal performs peristaltic movements due to a relative bending motion of the inner plate 2 and the outer plate 3 around the connection pin 1 and cannot be held in place. Consequently, not only the sealability of the rubber seal is deteriorated but also there may occur accidents of the rubber seal such as damage or destruction.